Estou implementando a gaveta de navegação no estilo pirulito com a biblioteca de suporte appcompat mais recente, mas o problema é que o ícone de hambúrguer nunca é exibido. Apenas o ícone Voltar é mostrado.

Este é o meu código de atividade

import android.os.Bundle;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.widget.Toolbar;
import android.view.View;

public class Home extends ActionBarActivity {

private DrawerLayout mDrawerLayout;
private ActionBarDrawerToggle mDrawerToggle;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    initViews();
}


private void initViews(){

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);


    toolbar.setTitleTextColor(getResources().getColor(android.R.color.white));
    setSupportActionBar(toolbar);

    mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,toolbar ,  R.string.drawer_open, R.string.drawer_close) { 

        /** Called when a drawer has settled in a completely closed state. */ 
        public void onDrawerClosed(View view) {
            super.onDrawerClosed(view);
            //getActionBar().setTitle(mTitle);
            //invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        } 

        /** Called when a drawer has settled in a completely open state. */ 
        public void onDrawerOpened(View drawerView) {
            super.onDrawerOpened(drawerView);
            //getActionBar().setTitle(mDrawerTitle);
            //invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        } 
    }; 


    // Set the drawer toggle as the DrawerListener 
    mDrawerLayout.setDrawerListener(mDrawerToggle);

    getSupportActionBar().setDisplayHomeAsUpEnabled(true); 
    getSupportActionBar().setHomeButtonEnabled(true); 

 }
}

Este é o meu arquivo de estilos

 <resources>
 <!-- Application theme. -->
<style name="Theme.Test" parent="@style/Theme.AppCompat.Light">

    <!-- customize the color palette -->
    <item name="colorPrimary">@color/primary</item>
    <item name="colorPrimaryDark">@color/primary_dark</item>
    <item name="colorAccent">@color/accent</item>
    <item name="windowActionBar">false</item>
    <item name="drawerArrowStyle">@style/Theme.Test.DrawerArrowStyle</item>
</style>

<style name="Theme.Test.DrawerArrowStyle" parent="@style/Widget.AppCompat.DrawerArrowToggle">
    <item name="spinBars">true</item>
    <item name="color">@android:color/white</item>
</style>

O arquivo de layout

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?attr/colorPrimary"
    android:minHeight="?attr/actionBarSize"
    app:theme="@style/ThemeOverlay.AppCompat.ActionBar" />

<android.support.v4.widget.DrawerLayout
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:layout_below="@+id/toolbar">

    <!-- The main content view -->

    <FrameLayout
        android:id="@+id/content_frame"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <!-- The navigation drawer -->

    <ListView
        android:id="@+id/left_drawer"
        android:layout_width="240dp"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="#111"
        android:choiceMode="singleChoice"
        android:divider="@android:color/transparent"
        android:dividerHeight="0dp" />
</android.support.v4.widget.DrawerLayout>

</RelativeLayout>

Nos dois casos, apenas a seta para trás é mostrada, eu li muitos posts, mas nada parece fazer a diferença. Qualquer ajuda seria apreciada.